An employee at the clinic Eugin prepares a sample of sperm and an egg for the process of fertilization on May 25, 2016 in Barcelona. (Photo credit LLUIS GENE/AFP/Getty Images)

The fields of science, technology, engineering and mathematics (STEM) have long been a boys’ club. Now, a new study suggests why the under-representation of women in these professions remains so persistent.

Starting in 2003, sociologists at the University of Michigan began tracking the career paths of a group of childless scientists. Eventually, many of those scientists did have children. But this life event affected their careers in different ways, depending on whether they were male or female. Among the new mothers, 40 percent left the STEM sector to find work in a different field, stayed in STEM but went down to part-time, or stopped working entirely. By contrast, only 23 percent of the new fathers changed, scaled back or paused their careers. The results suggest that in STEM professions, like many others, women are expected to assume a childcare role that forces them to choose between their career and their family.

This may be particularly true in the STEM world. “STEM work is often culturally less tolerant and supportive of caregiving responsibilities than other occupations,” said Erin Cech, the lead author of the study. Ironically, this may be precisely because these professions are dominated by men, and are therefore lacking in policies that could accommodate new parents who want to continue their careers, creating a vicious cycle.

“These young women are smart and tenacious,” said Ami Radunskaya, a mathematician at Pomona College in Claremont, California, referring to the women who choose a career path in STEM. Despite this, she said, motherhood often means being forced out of a work environment that is “at best, challenging to everyone and, at worst, openly sexist.”

This is a disgrace. Where is the UK foreign office in all of this? Aras Amiri now joins another British-Iranian, Nazanin Zaghari-Ratcliffe, in notorious Evin prison on bogus charges. @foreignofficehttps://t.co/DJX0knhdot